Blended nucleating agent compositions and methods

ABSTRACT

Certain thermoplastic additives that induce simultaneous good material properties and high nucleation efficacy are provided. Such additives include combinations of a phosphate salt and a dicarboxylate salt. This combination or blend may be provided in various ratios. A method for applying such a combination in a thermoplastic formulation is also disclosed. A thermoplastic formulation, which may or may not include polypropylene, is also disclosed in connection with the combination.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application claims priority to U.S. Provisional Application No.60/618,326; filed Oct. 13, 2004.

BACKGROUND OF THE INVENTION

Nucleating and clarifying agents are chemical compositions that may beadded to thermoplastic polymers to facilitate formation of the polymeras it changes from molten to solid form in the process ofcrystallization. Such additives may assist in reducing haze of polymericstructures. Many different chemical compositions are known for thispurpose. One major issue in the use of such agents is the amount ordegree of clarity that the agent or additive imparts to a finishedpolymeric article. Reducing haze and thereby increasing clarity of sucharticles is a constant endeavor in the plastics industry.

In general, the use of nucleating agents is a highly unpredictabletechnology area. Small or slight changes in a molecular structure candrastically change the ability of a given nucleating composition tonucleate or clarify effectively a polymer composition. There is a largeamount of unpredictability in the art of nucleating agents. There aremany unknowns regarding the effect of a given substance on polymermorphology during recrystallization of thermoplastics.

As an example of one type of nucleator, dibenzylidene sorbitol (DBS)compounds are common nucleator compounds, particularly for polypropyleneend products. Compounds such as1,3-O-2,4-bis(3,4-dimethylbenzylidene)sorbitol (hereinafter DMDBS),available from Milliken and Company of Spartanburg, S.C., USA under thetrade name Millad 3988®, provide excellent nucleation characteristicsfor target polypropylenes and other polyolefins. For example, of greatinterest is the compatibility of such compounds with different additiveswidely used within typical polyolefin (e.g., polypropylene,polyethylene, and the like) plastic articles.

Calcium stearate is a very popular acid neutralizer present withintypical polypropylene formulations to protect the end product fromcatalyst residue attack. Unfortunately, many nucleator compounds exhibitundesirable reactions with such compounds within polyolefin articles.For sodium, and other metal ions, it appears that the calcium ion fromthe stearate transfers positions with the sodium ions of the nucleatingagents, rendering the nucleating agents ineffective for their intendedfunction. As a result, such compounds sometimes exhibit unwantedplate-out characteristics and overall reduced nucleation performance (asmeasured, for example) by a decrease in crystallization temperatureduring and after polyolefin processing.

Problems that may be encountered with the standard nucleators notedabove include inconsistent nucleation due to dispersion problems,resulting in stiffness and impact variation in the polyolefin article.Substantial uniformity in polyolefin production is highly desirablebecause it results in relatively uniform finished polyolefin articles.If the resultant article does not contain a well-dispersed nucleatingagent, the entire article itself may suffer from a lack of rigidity andlow impact strength.

Furthermore, storage stability of nucleator compounds and compositionsis another potential problem with thermoplastic nucleators. Nucleatorcompounds are generally provided in powder or granular form to thepolyolefin manufacturer. Since uniform small particles of nucleatingagent may be imperative to provide the requisite uniform dispersion andperformance, such compounds must remain as small particles throughstorage. Certain nucleators, such as sodium benzoate, exhibit relativelyhigh degrees of hygroscopicity such that the powders made therefromhydrate easily resulting in particulate agglomeration. Such agglomeratedparticles may require further milling or other processing forde-agglomeration in order to achieve the desired uniform dispersionwithin the target thermoplastic. Furthermore, such unwantedagglomeration due to hydration may also cause feeding or handlingproblems for the user.

Solid bicyclo[2.2.1]heptane dicarboxylate salt-containing thermoplasticnucleating additive formulations are used and sold in the industry.Milliken and Company of Spartanburg, South Carolina distributescommercially nucleating agents of such metal salts, under the trade nameHYPERFORM®. One such product is known commercially as HPN-68®, which issold by Milliken and Company. U.S. Pat. Nos. 6,465,551; 6,559,211;6,521,685; and 6,583,206 relate to such compounds and their use. Thedicarboxylate salt is usually provided as a granular formulation, and isknown as a very good nucleating agent, particularly for applicationsthat require high crystallization temperatures (Tc).

Also of interest is the compatibility of such compounds with differentadditives widely used within typical polyolefin (e.g., polypropylene,polyethylene, ethylene copolymer polypropylene, (and the like) plasticarticles. As noted previously, calcium stearate compatibility isparticularly important. Unfortunately, many nucleators exhibit muchdeleterious nucleating efficacy with such compounds within polyolefinarticles. In order to avoid combinations of these standard nucleatorsand calcium salts, other nonionic acid neutralizers, such asdihydrotalcite (DHT4-A®), sometimes are necessary for use in conjunctionwith such nucleators.

Other known compounds useful for nucleation include sodium2,2′-methylene-bis-(4,6-di-tert-butylphenyl)phosphate (from Asahi DenkaKogyo K.K., known commercially as NA-11®), talc, and the like. Suchcompounds all impart high polyolefin crystallization temperatures;however, each also exhibits its own drawback for large-scale industrialapplications. U.S. Pat. Nos. 4,463,113 and 5,342,868 disclosecrystalline synthetic resin compositions of cyclic organophosphoricesters.

The structure that is believed to be used in connection with NA-11® isshown below:

A nucleating agent for polypropylene with a combination of positivematerial properties, like high Tc, low t_(1/2), isotropic shrinkage, andhigh stiffness would be highly desirable. Phosphate ester salts, likeNA-11® and NA-21® (manufactured by Asahi Denka Kogyo Kabushiki Kaisha ofJapan) are known to incur relatively high stiffness in injection moldedarticles. However, warpage caused by anisotropic shrinkage is often anundesired side effect of such materials. Such warpage is a disadvantageof using phosphate ester salts, and causes them to be undesirable inmany applications.

Thus, it may be seen that each nucleating composition has its advantagesand disadvantages. This has created a long-felt need in the polyolefinnucleator compound industry to provide compositions that minimize suchproblems and provide excellent peak crystallization temperatures for thetarget polyolefin. Unfortunately, it is a significant challenge to findnucleators exhibiting exceptionally high peak crystallizationtemperatures, low hygroscopicity, excellent thermal stability, highstiffness, and relatively low amounts of shrinkage or warpage infinished articles. For example, many nucleators cause shrinkage beyondthe limits required to keep molded articles within their sizespecifications. Shrinkage is a significant problem in the industry. Theinvention disclosed herein is directed at minimizing such problems.

Blends of more than one nucleator have been tried, but are not alwayssuccessful. Furthermore, this is a highly unpredictable area of thechemical arts, and there is usually no any way of knowing what will workuntil it is tried, and tested, and a relatively substantial amount ofwork is done.

U.S. Pat. No. 6,586,007 is directed to a combination of 3,4-dimethylbenzylidene sorbitol (DBS) and p-methylbenzylidene sorbitol(mDBS). U.S. Pat. Nos. 6,521,685 and 6,585,819 are directed to additivesthat comprise a blend of (a) bicyclic salts, and (b) benzylidenesorbitol acetals.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of this invention, including the bestmode shown to one of ordinary skill in the art, is set forth in thisspecification. The following Figures illustrate the invention:

FIG. 1 shows a comparison of crystallization temperature andcrystallization temperature half-time of homopolymer polypropylenenucleated by (1) Hyperform HPN-68® alone (2) NA-11UF® alone, as comparedto the inventive blends of (3) Hyperform® HPN-68® with NA-11®;

FIG. 2 shows the difference in flexural modulus compared to control;

FIG. 3 shows results of shrinkage measurements; and

FIG. 4 depicts results of anisotropy calculations.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made to the embodiments of the invention, one ormore examples of which are set forth below. Each example is provided byway of explanation of the invention, not as a limitation of theinvention. In fact, it will be apparent to those skilled in the art thatvarious modifications and variations can be made in this inventionwithout departing from the scope or spirit of the invention.

An object of the invention is to provide a thermoplastic additivecomposition that simultaneously induces high levels of nucleationefficiency as well as low degrees of haze (and thus excellent clarity)within target thermoplastic articles. Additionally, the inventionprovides a nucleator/clarifier additive composition that may be used invarious polyolefin media for use in many end uses.

Accordingly, this invention is directed to a nucleating or clarifyingagent composition that is a combination of a phosphate salt and adicarboxylate salt. This combination or blend may be provided in variousratios. The invention also includes a method for applying such acombination in a thermoplastic formulation, and also the formulationcontaining the combination.

In general, it is widely known that a combination of two different typesof nucleating agents in one plastic or thermoplastic leads to the resultthat one of the nucleators-overrides essentially all the effects of theother nucleating agent. This is a common and widely understood principlein the art of nucleation.

However, in the practice of the invention, surprisingly, it has beendiscovered that the addition of two specific types of nucleating agents(set forth herein) will change only one of the properties (stiffness).This is the case, even though the crystallization temperatures andcrystallization half times of the resulting nucleated polymers arebarely affected.

It would be expected that the combination of: (a) a phosphate saltnucleating agent, and (2) a dicarboxylate salt nucleating agent, (3)when combined in a single plastic or thermoplastic formulation: wouldnot have had any significant effects upon the crystallizationtemperature or stiffness. However, this unexpectedly discovered highlydesirable combination provides, in certain circumstances, acrystallization temperature (Tc) that is substantially higher than theTc's of both the named single nucleators when used alone. Furthermore,the stiffness of the nucleator combination is higher or equal to thestiffness of using each alone. These are surprisingly and beneficialresults, which are novel and nonobvious over known prior art nucleatingagent compositions. Further, these results and these particular blendsare unknown in the industry.

As used herein, the term “thermoplastic” refers generally to a polymericmaterial that will melt upon exposure to sufficient heat but will retainits solidified state upon cooling. “Thermoplastic” refers to plasticshaving crystalline or semi-crystalline morphology upon cooling aftermelt-formation, usually by the use of a mold or like article. Particulartypes of polymers contemplated within such a definition include, withoutlimitation, polyolefins (such as polyethylene, polypropylene,polybutylene, and any combination thereof), polyamides (such as nylon),polyurethanes, polyester (such as polyethylene terephthalate), and thelike (as well as any combinations thereof).

Thermoplastics have been utilized in a variety of end-use applications,including storage containers, medical devices, food packages, plastictubes and pipes, shelving units, and the like. Such base compositions,however, must exhibit certain physical characteristics in order topermit widespread use. Specifically within polyolefins, for example,uniformity in arrangement of crystals upon crystallization is anecessity to provide an effective, durable, and versatile polyolefinarticle. In order to achieve such desirable physical properties, it hasbeen known that certain compounds and compositions provide nucleationsites for polyolefin crystal growth during molding or fabrication.Generally, compositions containing such nucleating compounds crystallizeat a much faster rate than un-nucleated polyolefin. Such crystallizationat higher temperatures results in reduced fabrication cycle times and avariety of improvements in physical properties, such as stiffness.

Such compounds and compositions that provide faster and or higherpolymer crystallization temperatures are popularly known as nucleators.Such compounds provide nucleation sites for crystal growth duringcooling of a thermoplastic molten formulation.

In one embodiment of the invention, the combination comprises both amulti-cyclic phosphate salt and a metal or organic salts of saturatedbicyclic dicarboxylates.

Such a method includes the steps of (a) providing a molten thermoplasticformulation; (b) introducing to such formulation and mixing therein acomposition comprising at least one phosphate-containing salt and atleast one dicarboxylate-containing salt, and (c) allowing the resultantcomposition of step “b” to cool into a thermoplastic article.

Salts of Dicarboxylates

Some particular, non-limiting examples of such novel nucleator compoundsinclude the metal or organic salts of saturated [2.2.1]bicyclicdicarboxylates, and most preferably of these types of compoundsconforming to Formula (I)

wherein M₁ and M₂ are the same or different, or M₁ and M₂ are combinedto from a single moiety, and are independently selected from the groupconsisting of metal or organic cations, and R₁, R₂, R₃, R₄, R₅, R₆, R₇,R₈, R₉, and R₁₀ are individually selected from the group consisting ofhydrogen, C₁-C₉ alkyl, hydroxyl, C₁-C₉ alkoxy, C₁-C₉ alkyleneoxy, amine,and C₁-C₉ alkylamine, halogen, phenyl, alkylphenyl, and geminal orvicinal C₁-C₉ carbocyclic.

The metal cations are selected from the group consisting of calcium,strontium, barium, magnesium, aluminum, silver, sodium, lithium,rubidium, potassium, and the like. Within that scope, group I and groupII metal ions are generally quite effective. Among the group I and IIcations, sodium, potassium, calcium and strontium are useful, whereinsodium and calcium are very useful. Furthermore, the M₁ and M₂ groupsmay also be combined to form a single metal cation (such as calcium,strontium, barium, magnesium, aluminum, and the like). Although thisinvention encompasses all stereochemical configurations of suchcompounds, the cis configuration is preferred wherein cis-endo is one ofthe most preferred embodiments. The preferred embodiment polyolefinarticles and additive compositions for polyolefin formulationscomprising at least one of such compounds are also encompassed withinthis invention.

A blended nucleating or clarifying composition for thermoplastics isemployed, comprising a blend of a first nucleating agent of a carboxylicacid salt compound and a second nucleating agent of a Bis-phenolphosphate. The first nucleating agent is selected from the groupconforming with the structure of Formula (I)

wherein M₁ and M₂ are the same or different, or M₁ and M₂ are combinedto from a single moiety, and are independently selected from the groupconsisting of metal or organic cations, and R₁, R₂, R₃, R₄, R₅, R₆, R₇,R₈, R₉, and R₁₀ are individually selected from the group consisting ofhydrogen, C₁-C₉ alkyl, hydroxyl, C₁-C₉ alkoxy, C₁-C₉ alkyleneoxy, amine,and C₁-C₉ alkylamine, halogen, phenyl, alkylphenyl, and C₁-C₉carbocyclic.

Cyclic Phosphates

In some instances, the Bis-phenol phosphates comprise the formula:

wherein: R is selected from the group consisting of: a carbon-to-carbonbond; thio sulfur —S—; and alkylidene

in which R₃ and R₄ are selected from the group consisting of hydrogen,alkyl having from one to about eighteen carbon atoms, and cycloalkyl,including cycloalkylidene in which R₃ and R₄ are taken together as partof a cycloalkylene ring, having from three to about twelve carbon atoms;and in which R₁ and R₂ each are selected from the group consisting of:hydrogen, alkyl having from about one to about eighteen carbon atoms;and cycloalkyl having from about 3-12 carbon atoms. Typically, M is ametal atom selected from alkali metal atoms or alkaline earth metalatoms; and n is the valence of the metal atom M, and ranges from 1 to 2.

R is alkylidene

and R₁ and R₂ may be alkyl. In some embodiments, R is thio sulfur —S—and R₁ and R₂ are each alkyl. For some applications, R is acarbon-to-carbon bond and R₁ and R₂ are each alkyl. R may becycloalkylidene and R₁ and R₂ may be each alkyl.

In yet other applications, R₁ and R₂ may be t-alkyl, and R may comprisealkylidene. R may be provided as a carbon-to-carbon bond. Bis-phenolphosphates may be employed in which R is thio sulfur —S—. R₃ and R₄ maybe each hydrogen as well. Furthermore, R₃ may be hydrogen and R₄ may bealkyl. R₃ may be hydrogen and R₄ may be cycloalkyl. Alternatively, R₃and R₄ may be taken together as cycloalkylidene. Bis-phenol phosphatesmay be provided in which M is an alkali metal. M may be an alkalineearth metal. M may be a polyvalent metal. R₁ and R₂ may be each tertiaryalkyl. R₁ may be hydrogen and R₂ may be tertiary alkyl. R₁ may behydrogen and R₂ may be cycloalkyl.

Exemplary R alkylidene include at least the following, but are notlimited to the following: methylidene, ethylidene, propylidene,isopropylidene, butylidene, isobutylidene, sec-butylidene,tert-butylidene, amylidene, hexylidene, heptylidene, octylidene,isooctylidene, 2-ethyl hexylidene, nonylidene and decylidene;cyclohexylidene, cycloheptylidene, methyl cyclohexylidene, ethylcyclohexylidene, and cyclooctylidene.

Exemplary R₁ and R₂, R₃ and R₄ alkyl include methyl, ethyl, propyl,isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, amyl, t-amyl, hexyl,heptyl, octyl, 2-ethylhexyl, t-octyl, nonyl, decyl, undecyl, dodecyl,tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl and octadecyl.

Exemplary R₁ and R₂, R₃ and R₄ cycloalkyl include cyclopropyl,cyclobutyl, cyclopentyl, methylcyclopentyl, cyclohexyl,methylcyclohexyl, cycloheptyl, cyclooctyl and cyclododecyl.

Exemplary M monovalent metals include Li, Na, Ki; exemplary bivalentmetals include Be, Ca, Sr, Ba, Zn, and Cd; Exemplary trivalent andtetravalent metals include Al, Ge, Sn, Pb, Ti, Zr, Sb, Cr, Bi, Mo, Mn,Fe, Co and Ni. Among these metals, the alkali metals such as Li, Na andK and the alkaline earth metals such as Mg, Ca, Sr and Ba are known tobe useful.

Compounds useful for nucleation in the combination of the inventioninclude, but are not limited to, sodium2,2′-methylene-bis-(4,6-di-tert-butylphenyl)phosphate (from Asahi DenkaKogyo K.K., known commercially as NA-11®), talc, and the like. Theinvention may employ essentially any cyclic group having a phosphateattached. Bicylic, tricyclic, and the like may be employed, with aphosphate salt, as one example.

In one embodiment, the combination of the invention comprises both amulti-cyclic phosphate salt and organic salts of saturated bicyclicdicarboxylates.

As indicated, the structure of NA-11® is one example of aphosphate-containing nucleator that may be employed. Its structure isshown below:

This invention, in one embodiment, brings a combination of the positiveaspects from both phosphate ester salts and Hyperform® HPN-68 (a productof Milliken and Company of Spartanburg, S.C., USA), being: Highcrystallization temperatures (substantially equal to Hyperform® HPN-68);Low crystallization half times (substantially equal to Hyperform®HPN-68); Isotropic shrinkage (between control and Hyperform® HPN-68);Shrinkage reduction (between NA-11 and Hyperform® HPN-68); Highperceived stiffness (substantially equal to NA-11®).

Although polyolefins are preferred, the nucleating agents of the presentinvention are not restricted to polyolefins, and may also givebeneficial nucleation properties to polyesters such as polyethyleneterephthalate (PET), polybutylene terephthalate (PBT), and polyethylenenaphthalate (PEN), as well as polyamides such as Nylon 6, Nylon 6,6, andothers. Generally, many different types of thermoplastic compositionshaving some crystalline content may be improved with the nucleatingagents of the present invention.

EXAMPLES

A series of nucleators was compounded into homopolymer polypropylene(Basell Pro-fax® 6301 NT) together with a standard stabilization package(800 ppm calcium stearate, 1500 ppm Irganox® B215). Plaques (dimensions:50×70×3 mm³) were injection molded from the resulting compounds. Thermalproperties were determined with a Perkin Elmer Diamond DSC. Mechanicalproperties (flexural modulus) were measured on a Lloyd LR10 tensiletester with a 500 N load cell.

Thermal Properties

The crystallization temperature was determined by heating approximately2.5 mg sample to 220° C., keeping it at this temperature for 2 minutesto remove any thermal history, and cooling down to 50° C. at a coolingrate of 20° C./min. The peak of the crystallization exotherm is regardedas the crystallization temperature.

The crystallization half time was determined by heating approximately5.0 mg sample to 220° C., keeping it at this temperature for 2 minutesto remove any thermal history, and cooling down to 135° C. at a coolingrate of 200° C./min. The time after which half of the sample hadcrystallized is regarded as the crystallization half time.

FIG. 1 shows the thermal properties measurements as a function ofnucleator content. Values are provided in Table 1 below.

The results in FIG. 1 show that Hyperform® HPN-68 nucleatedpolypropylene samples at concentrations over 500 ppm of nucleator havehigher crystallization temperatures than any of the NA-11® nucleatedpolymers. Blends of Hyperform HPN-68® and NA-11® nucleated polymers allhave higher crystallization temperatures than the NA-11® nucleatedpolymers, irrespective of their composition. This is a surprising andunexpected result. The crystallization half times follow the sametrends.

Mechanical Properties

The flexural modulus was determined from three-point bending forcemeasurements on injection molded plaques (50×70×3 mm³). Measurementswere carried out at 1.28 mm/minute bending speed on a 48 mm supportspan. The reported values are averages of five measurements after eightdays of annealing at room temperature.

The results of the flexural modulus measurements are graphicallydepicted in FIG. 2; values are in Table 2 in the appendix. FIG. 2 showsthe difference in flexural modulus compared to control. All nucleatedsamples have a higher flexural modulus than the control samples.However, it can be easily seen that the values for NA-11® nucleatedhomopolymer are significantly higher than for the Hyperform HPN-68®nucleated samples, irrespective of the concentration. Furthermore, thereis a significant increase of flexural modulus with the concentration ofNA-11®, while there is not for the Hyperform HPN-68® nucleated samples.

Samples in which both Hyperform® HPN-68 and NA-11 are present, havehigher flexural moduli than samples with just Hyperform® HPN-68, andequal moduli compared to samples with just NA-11® in concentrations ofHyperform® HPN-68 and NA-11® combined.

Shrinkage and Shrinkage Anisotropy

Shrinkage was determined from injection molded plaques ((50×70×3 mm³) inboth machine direction (MD) and transverse direction (TD). Shrinkageanisotropy is as in Formula 1. Equation  1: $\quad\begin{matrix}{{{anisotropy} = {\frac{\text{relative~~shrinkage~~in}\quad{TD}}{\text{relative~~shrinkage~~in}\quad{MD}} - 1}}{{Definition}\quad{of}\quad{anisotropy}}} & \quad\end{matrix}$Relative shrinkage is defined in Formula 2. Equation  2$\quad{{{relative}\quad{shrinkage}} = {\frac{L_{0} - L}{L_{0}}*100\%}}$  Definition  of  relative  shrinkage.Where L₀ is the size of the mold, and L is the size of the plaque 2 daysafter injection molding.

Results of the shrinkage measurements are shown in FIG. 3; results ofthe anisotropy calculations are shown in FIG. 4. The values are in Table3.

Hyperform® HPN-68 nucleated samples show the highest shrinkage in bothmachine direction (MD) and transverse direction (TD) and shrinkage isslightly dependent on HPN-68 concentration. Shrinkage in the NA-11nucleated samples is different for TD and MD; in the MD, the shrinkageis lower than control, while in the TD shrinkage is equal to or higherthan control. The samples containing both Hyperform® HPN-68 and NA-11®have shrinkages that are equal or slightly higher than control in bothdirections, but lower than the Hyperform® HPN-68 nucleated samples.

Effects on anisotropy are shown in FIG. 4.

Materials nucleated with only NA-11® have a high tendency foranisotropic shrinkage compared to control materials. This anisotropicshrinkage is not significantly dependent on the concentration of NA-11®.Materials nucleated with Hyperform® HPN-68 have a tendency to shrinkmore isotropically than control materials. Shrinkage induced byHyperform® HPN-68 tends to be more isotropic by increasing theconcentration of the nucleating agent.

Samples containing both Hyperform® HPN-68 and NA-11® have anisotropyvalues comparable or slightly higher than samples with just HyperformHPN-68, and slightly lower or equal compared to control material.

Homopolymer polypropylene nucleated with a mixture of Hyperform® HPN-68and NA-11® surprisingly and unexpectedly provides several beneficialproperties in the polymer. These may include, but are not limited to,the following positive properties: High crystallization temperatures(may be substantially equal to Hyperform® HPN-68); Low crystallizationhalf times (may be substantially equal to Hyperform® HPN-68); Isotropicshrinkage (between control and Hyperform® HPN-68); Shrinkage reduction(between NA-11® and Hyperform® HPN-68); High perceived stiffness(substantially equal to NA-11®).

Sheet extrusion and thermoforming are applications besides injectionmolding where this blend could be beneficial. The stiffness of NA-11 andisotropic shrinkage of Hyperform® HPN-68 are a highly desirablecombination for both applications.

Accordingly, this invention is directed to a nucleating or clarifyingagent composition that is a combination of a phosphate salt and adicarboxylate salt. One example of the phosphate salt is the NA-11®, asshown above. However, many other phosphate salts could be used, and theinvention is not limited to any particular phosphate salt. Thiscombination or blend may be provided in various ratios. The inventionalso includes a method for applying such a combination in athermoplastic formulation, and also the formulation containing thecombination.

In the blends of the invention, synergistic effects are evident. Thatis: the Tc of combination is higher that Tc's of each component alone,although somewhat lower than hyperform at the total concentration ofboth: NA-11 ® (500 ppm): 121.3° C. HPN-68 ® (500 ppm): 123.6° C.HPN-68 ® + NA-11 (both 500): 126.9° C. HPN-68 ® (1000 ppm): 128.1° C.

The effect of the combination is surprisingly high, and also beneficialfor many applications. As to stiffness, it is observed to be about thesame as with Tc. That is, the stiffness is higher or equal than bothalone, but somewhat lower or equal than NA-11® at the totalconcentration of both. NA-11 ® (1000 ppm): 1695 MPa HPN-68 ® (1000 ppm):1623 MPa HPN-68 + NA-11 ® (both 1000): 1727 MPa NA-11 (2000 ppm): 1731Mpa

Also, these values should be noted as well, set forth below. NA-11 ®(1000 ppm): 1695 MPa HPN-68 ® (500 ppm): 1614 MPa HPN-68 + NA-11 ®(500 + 1000): 1710 MPa NA-11 (1500 ppm): 1712 MPa

Example 1 Hyperform HPN-68:NA-11=500:500

To a mixture of 200 g polypropylene homopolymer fluff was added 5.0 g ofHyperform Concentrate Hi5-5 [Hi5-5 is a 5% concentrate form ofHyperform® HPN-68®, and also is a product of Milliken and Company ofSpartanburg, S.C., USA]; 0.25 g of NA-11®(2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium) and astandard stabilization package (0.75 g Irganox® B-215 and 0.40 g calciumstearate). To this mixture, enough polypropylene homopolymer fluff wasadded for the total weight to reach 500 g. The resulting mixture wasphysically blended with a ribbon blender for at least five minutes.

Example 2 Hyperform® HPN-68:NA-11=100:1000

To a mixture of 200 g polypropylene homopolymer fluff was added 1.0 g ofHyperform® Concentrate Hi5-5, 0.50 g of NA-11®(2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium) and astandard stabilization package (0.75 g Irganox® B215 and 0.40 g calciumstearate). To this mixture, enough polypropylene homopolymer fluff wasadded for the total weight to reach 500.00 g. The resulting mixture wasphysically blended with a ribbon blender for at least five minutes.

Example 3 Hyperform® HPN-68:NA-11=200:1000

To a mixture of 200 g polypropylene homopolymer fluff was added 2.0 g ofHyperform® Concentrate Hi5-5, 0.50 g of NA-11(2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium) and astandard stabilization package (0.75 g Irganox® B-215 and 0.40 g calciumstearate). To this mixture, enough polypropylene homopolymer fluff wasadded for the total weight to reach 500 g. The resulting mixture wasphysically blended with a ribbon blender for at least five minutes.

Example 4 Hyperform® HPN-68:NA-11=500:1000

To a mixture of 200 g polypropylene homopolymer fluff was added 5.0 g ofHyperform® Concentrate Hi5-5, 0.50 g of NA-11®(2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium) and astandard stabilization package (0.75 g Irganox® B215 and 0.40 g calciumstearate). To this mixture, enough polypropylene homopolymer fluff wasadded for the total weight to reach 500 g. The resulting mixture wasphysically blended with a ribbon blender for at least five minutes.

Example 5 Hyperform® HPN-68:NA-11=750:1000

To a mixture of 200 g polypropylene homopolymer fluff was added 7.5 g ofHyperform ® Concentrate Hi5-5, 0.50 g of NA-11(2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium) and astandard stabilization package (0.75 g Irganox® B-215 and 0.40 g calciumstearate). To this mixture, enough polypropylene homopblymer fluff wasadded for the total weight to reach 500.00 g. The resulting mixture wasphysically blended with a ribbon blender for at least five minutes.

Example 6 Hyperform® HPN-68:NA-11=1000:1000

To a mixture of 200 g polypropylene homopolymer fluff was added 10.0 gof Hyperform® Concentrate Hi5-5, 0.50 g of NA-11(2,2′-METHYLENE-BIS(4,6-DI-TERT-BUTYLPHENYL)PHOSPHATE SODIUM) and astandard stabilization package (0.75 g Irganox® B215 and 0.40 g calciumstearate). To this mixture, enough polypropylene homopolymer fluff wasadded for the total weight to reach 500 g. The resulting mixture wasphysically blended with a ribbon blender for at least five minutes.

Example 7 Hyperform® HPN-68 500 ppm—Comparative

To a mixture of 200 g polypropylene homopolymer fluff was added 5.0 g ofHyperform® Concentrate Hi5-5 and a standard stabilization package (0.75g Irganox® B215 and 0.40 g calcium stearate). To this mixture, enoughpolypropylene homopolymer fluff was added for the total weight to reach500.00 g. The resulting mixture was physically blended with a ribbonblender for at least five minutes.

Example 8 Hyperform® HPN-68 1000 ppm—Comparative

To a mixture of 200 g polypropylene homopolymer fluff was added 10.0 gof Hyperform® Concentrate Hi5-5 and a standard stabilization package(0.75 g Irganox® B215 and 0.40 g calcium stearate). To this mixture,enough polypropylene homopolymer fluff was added for the total weight toreach 500.00 g. The resulting mixture was physically blended with aribbon blender for at least five minutes.

Example 9 NA-11® 1000 ppm—Comparative

To a mixture of 200 g polypropylene homopolymer fluff was added 0.50 gof NA-11® (2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium)and a standard stabilization package (0.75 g Irganox® B215 and 0.40 gcalcium stearate). To this mixture, enough polypropylene homopolymerfluff was added for the total weight to reach 500.00 g. The resultingmixture was physically blended with a ribbon blender for at least fiveminutes.

Example 10 Extrusion and Injection Molding

The mixtures obtained in examples 1 to 7 were melt-compounded on aKillion® KLB 100 (L/D ratio 32:1-single screw D=1″). The temperatureprofile was set at 205 ° C. (feed)-220° C.-230° C.-230° C. (die) and ascreen pack screen pack (40/300/100/60 mesh) was used. Plaques ofdimensions 70×50×3 mm³ (length×width×thickness) were injection moldedfrom the melt-compounded blends on an Arburg Allrounder 221-55-250 with18 mm diameter screw. The temperature profile was set as follows, 200°C. (feed)-215° C.-215° C.-215° C. (nozzle).

Example 11 Physical Testing

Crystallization temperatures were determined with a Perkin Elmer DiamondDSC on small pieces (˜2.5 mg) of injection molded plaques. The followingtemperature profile was used: heating at 20° C./min to 220° C., holdingat 220° C. for 2 minutes, cooling at 20° C./min to 50° C. Thecrystallization temperature T_(c) was determined in the cooling run.Subsequent heating at 20° C. to 220° C. provided the meltingtemperature. Shrinkage was determined by measuring the injection molded3 mm plaques 48 hours after injection molding with a caliper. Shrinkagein both machine as well as transverse direction were calculated by theformula shrinkage=(L₀−L)/L₀*100%, in which L₀ is the mold dimension andL is the size of the injection molded plaque after 48 hours. Shrinkageanisotropy is determined by the formula anisotropy=(shrinkageTD)/(shrinkage MD)−1. Flexural modulus is determined 7 days afterinjection molding on 3 mm plaques.

Example 12 Hyperform® HPN-68:NA-11=500:500, Random Copolymer

To a mixture of 200 g polypropylene random copolymer fluff was added 5.0g of Hyperform® Concentrate Hi5-5, 0.25 g of NA-11(2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium) and astandard stabilization package (0.75 g Irganox® B215 and 0.40 g calciumstearate). To this mixture, enough polypropylene random copolymer fluffwas added for the total weight to reach 500.00 g. The resulting mixturewas physically blended with a ribbon blender for at least five minutes.

Example 13 Hyperform® HPN-68:NA-11=500:1000. Random Copolymer

To a mixture of 200 g polypropylene random copolymer fluff was added 5.0g of Hyperform Concentrate Hi5-5, 0.50 g of NA-11(2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium) and astandard stabilization package (0.75 g Irganox B215 and 0.40 g calciumstearate). To this mixture, enough polypropylene random copolymer fluffwas added for the total weight to reach 500.00 g. The resulting mixturewas physically blended with a ribbon blender for at least five minutes.

Example 14 Hyperform® HPN-68:NA-11=1000:1000, Random Copolymer

To a mixture of 200 g polypropylene random copolymer fluff was added10.0 g of Hyperform® Concentrate Hi5-5, 0.50 g of NA-11(2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate sodium) and astandard stabilization package (0.75 g Irganox® B215 and 0.40 g calciumstearate). To this mixture, enough polypropylene random copolymer fluffwas added for the total weight to reach 500.00 g. The resulting mixturewas physically blended with a ribbon blender for at least five minutes.

It is understood by one of ordinary skill in the art that the presentdiscussion is a description of exemplary embodiments only, and is notintended as limiting the broader aspects of the present invention, whichbroader aspects are embodied in the exemplary constructions. Theinvention is shown by example in the appended claims.

1. A blended nucleating or clarifying composition for thermoplasticscomprising a blend of more than one species of nucleating agent, saidblend comprising at least the following: (a) a first nucleating agent ofa carboxylic acid salt compound; and (b) a second nucleating agent of aphosphate-containing salt compound.
 2. The blended composition of claim1 wherein said first nucleating agent is selected from the groupconforming with the structure of Formula (I)

wherein M₁ and M₂ are the same or different, or M₁ and M₂ are combinedto from a single moiety, and are independently selected from the groupconsisting of metal or organic cations, and R₁, R₂, R₃, R₄, R₅, R₆, R₇,R₈, R₉, and R₁₀ are individually selected from the group consisting ofhydrogen, C₁-C₉ alkyl, hydroxyl, C₁-C₉ alkoxy, C₁-C₉ alkyleneoxy, amine,and C₁-C₉ alkylamine, halogen, phenyl, alkylphenyl, and C₁-C₉carbocyclic.
 3. The composition of claim 2 wherein said metal or organiccation is a metal cation selected from the group consisting of: Group Iand Group II metal ions.
 4. The composition of claim 2 wherein saidmetal or organic cation is selected from the group consisting of:sodium, potassium, calcium, lithium, rubidium, barium, magnesium, andstrontium, silver, zinc, aluminum.
 5. The composition of claim 4 whereinsaid metal or organic cation comprises sodium or calcium.
 6. Athermoplastic article comprising the blended composition of claim
 1. 7.A thermoplastic article comprising the blended composition of claim 2.8. A thermoplastic article comprising the blended composition of claim3.
 9. A thermoplastic article comprising the blended composition ofclaim
 4. 10. A thermoplastic article comprising the blended compositionof claim
 5. 11. The article of claim 6 wherein said thermoplasticarticle comprises polypropylene.
 12. The article of claim 7 wherein saidthermoplastic article comprises polypropylene.
 13. The article of claim8 wherein said thermoplastic article comprises polypropylene.
 14. Thearticle of claim 9 wherein said thermoplastic article comprisespolypropylene.
 15. The article of claim 10 wherein said thermoplasticarticle comprises polypropylene.
 16. A blended nucleating or clarifyingcomposition for thermoplastics comprising a blend of more than onespecies of nucleating agent, said blend comprising at least thefollowing: (a) a first nucleating agent of a carboxylic acid saltcompound; said first nucleating agent being selected from the groupconforming with the structure of Formula (I)

wherein M₁ and M₂ are the same or different, or M₁ and M₂ are combinedto from a single moiety, and are independently selected from the groupconsisting of metal or organic cations, and R₁, R₂, R₃, R₄, R₅, R₆, R₇,R₈, R₉, and R₁₀ are individually selected from the group consisting ofhydrogen, C₁-C₉ alkyl, hydroxyl, C₁-C₉ alkoxy, C₁-C₉ alkyleneoxy, amine,and C₁-C₉ alkylamine, halogen, phenyl, alkylphenyl, and C₁-C₉carbocyclic; and (b) a second nucleating agent of a Bis-phenolphosphate.
 17. The composition of claim 16, wherein said Bis-phenolphosphate comprises the formula:

wherein: R is selected from the group consisting of: a carbon-to-carbonbond; thio sulfur —S—; and alkylidene

in which R₃ and R₄ are selected from the group consisting of hydrogen,alkyl having from one to about eighteen carbon atoms, and cycloalkyl,including cycloalkylidene in which R₃ and R₄ are taken together as partof a cycloalkylene ring, having from three to about twelve carbon atoms;R₁ and R₂ each are selected from the group consisting of: hydrogen,alkyl having from about one to about eighteen carbon atoms; andcycloalkyl having from about 3-12 carbon atoms; M is a metal atomselected from the group consisting of: alkali metal atoms and alkalineearth metal atoms; and n is the valence of the metal atom M, and rangesfrom 1 to
 2. 18. Bis-phenol phosphates according to claim 17 wherein Ris alkylidene

and said R₁ and R₂ are both alkyl.
 19. Bis-phenol phosphates accordingto claim 17 in which R is thio sulfur —S— and R₁ and R₂ are both alkyl.20. Bis-phenol phosphates according to claim 17 in which R is acarbon-to-carbon bond and R₁ and R₂ are both alkyl.
 21. Bis-phenolphosphates according to claim 17 in which R is cycloalkylidene and R₁and R₂ are both alkyl.
 22. Bis-phenol phosphates according to claim 17in which R₁ and R₂ are each t-alkyl and R comprises alkylidene. 23.Bis-phenol phosphates according to claim 17 in which R is acarbon-to-carbon bond.
 24. Bis-phenol phosphates according to claim 17in which R is thio sulfur —S—.
 25. Bis-phenol phosphates according toclaim 17 in which R is alkylidene according to the structure:


26. Bis-phenol phosphates according to claim 25 in which R₃ and R₄ areboth hydrogen.
 27. Bis-phenol phosphates according to claim 25 in whichR₃ is hydrogen and R₄ is alkyl.
 28. Bis-phenol phosphates according toclaim 25 in which R₃ is hydrogen and R₄ is cycloalkyl.
 29. Bis-phenolphosphates according to claim 25 in which R₃ and R₄ are taken togetheras cycloalkylidene.
 30. Bis-phenol phosphates according to claim 25 inwhich M is an alkali metal.
 31. Bis-phenol phosphates according to claim25 in which M is an alkaline earth metal.
 32. Bis-phenol phosphatesaccording to claim 25 in which M is a polyvalent metal.
 33. Bis-phenolphosphates according to claim 25 in which R₁ and R₂ are each tertiaryalkyl.
 34. Bis-phenol phosphates according to claim 25 in which R₁ ishydrogen and R₂ is tertiary alkyl.
 35. Bis-phenol phosphates accordingto claim 25 in which R₁ is hydrogen and R₂ is cycloalkyl.
 36. Athermoplastic article comprising the blended composition of claim 16.37. A thermoplastic article comprising the blended composition of claim17.
 38. A thermoplastic article comprising the blended composition ofclaim
 18. 39. A blended nucleating or clarifying composition forthermoplastics comprising a blend of more than one species of nucleatingagent, said blend comprising at least the following: (a) a firstnucleating agent of a carboxylic acid salt compound; and (b) a secondnucleating agent of a phosphate-containing salt compound; (c) furtherwherein said first nucleating agent and said second nucleating agent areprovided in said thermoplastic at a predetermined ratio.
 40. Thecomposition of claim 39 wherein said ratio of (a):(b) comprises about1:10.
 41. The composition of claim 39 wherein said ratio of (a):(b)comprises about 1:5.
 42. The composition of claim 39 wherein said ratioof (a):(b) comprises about 1:3.
 43. The composition of claim 39 whereinsaid ratio of (a):(b) comprises about 1:2.
 44. The composition of claim39 wherein said ratio of (a):(b) comprises about 1:1.
 45. Thecomposition of claim 40 wherein said blended composition is provided insaid thermoplastic at concentration level of (a) of about 100 ppm. 46.The composition of claim 41 wherein said blended composition is providedin said thermoplastic at a concentration level of (a) of about 200 ppm.47. The composition of claim 42 wherein said blended composition isprovided in said thermoplastic at an overall concentration level of (a)of about 1500 ppm.
 48. The composition of claim 43 wherein said blendedcomposition is provided in said thermoplastic at a concentration levelof (a) of about 500 ppm.
 49. The composition of claim 44 wherein saidblended composition is provided in said thermoplastic at a concentrationlevel of (a) of between about 500 and about 1000 ppm.
 50. A blendednucleating or clarifying composition for thermoplastics comprising ablend of more than one species of nucleating agent, said blendcomprising at least the following: (a) a first nucleating agent of acarboxylic acid salt compound; said first nucleating agent beingselected from the group conforming with the structure of Formula (I)

wherein M₁ and M₂ are the same or different, or M₁ and M₂ are combinedto from a single moiety, and are independently selected from the groupconsisting of metal or organic cations, and R₁, R₂, R₃, R₄, R₅, R₆, R₇,R₈, R₉, and R₁₀ are individually selected from the group consisting ofhydrogen, C₁-C₉ alkyl, hydroxyl, C₁-C₉ alkoxy, C₁-C₉ alkyleneoxy, amine,and C₁-C₉ alkylamine, halogen, phenyl, alkylphenyl, and C₁-C₉carbocyclic; and (b) a second nucleating agent of a Bis-phenolphosphate, said second nucleating agent having the structure providedbelow:

wherein t-Bu refers to a tertiary butyl group.